Warren Beatty stripped the American presidential campaign of its only hope of a patina of glamour yesterday when the movie star finally made it plain that he will not be a candidate. Beatty indicated that three 'f-words' were behind his decision: a desire to retain his freedom; an unwillingness to make a fool of himself; and the fear that he might do more to damage than promote the liberal causes he supports.

The Hollywood actor, director and producer - active in Democratic politics for more than 30 years - rules himself out of a run for the White House in his first interview on the subject since he started flirting with it six months ago.

'I feel good about speaking up,' he says in the February edition of Vanity Fair. 'I wouldn't feel good if I hadn't. It seems to me that the effect has been positive, that I've not yet made too much of a fool of myself - at least, I don't think I have.'

He goes on: 'I have not diminished the importance of the issues. One has to be very, very careful not to be an unwitting party to making what most people consider to be unfashionably liberal ideas appear to be more unpopular than they really are.'

Beatty, an early victim of Clinton fatigue, says that much of his message might fall on deaf ears: universal medical cover; action against exploitation of workers; and rebuilding the schools system and raising teachers' pay.

But even though a poll found that, of putative presidential candidates, only property tycoon Donald Trump and rightwing Republican Pat Buchanan were viewed more negatively, the star said he might run at a later date.